1. Technical Field
The present invention relates to a control system for storing data indicating a state of each unit of a vehicle, and controlling each unit of the vehicle based on the relevant data.
2. Related Art
In recent years, a demand for a control system that verifies a state of each unit of the vehicle at the time of engine startup based on initial information of each unit of the vehicle and/or setting information and the like set in advance by a passenger and the like and controls each unit of the vehicle based on the verification result is increasing with higher function of the vehicle.
In the control system, the ECU (Electronic Control Unit) for controlling a seat stores data containing initial information including a reference position of the seat, a reference angle of a backrest and the like, and setting information including a seat position, a backrest angle, and the like for every seat set in advance by the passenger and the like in a storage unit including a non-volatile storage medium such as an EEPROM (Electronically Erasable and Programmable Read Only Memory). The data indicating the state of the seat (seat position, backrest angle, and the like) at the time of the engine startup is stored in a temporary storage unit including a volatile storage medium such as a RAM (Random Access Memory).
If there is a difference between the data stored in the storage unit and the data stored in the temporary storage unit, that is, if the seat position or the backrest angle at the time of the engine startup and the seat position or the backrest angle set in advance differ, the ECU moves the seat position and inclines the backrest to the position and the angle set in advance based on the data stored in the storage unit. The above described cases where the operation of moving the seat and inclining the backrest is performed include a case performed by the ECU when recognizing that the operation switch has been operated by the passenger, and a case automatically performed by the ECU after the engine startup and the like.
Similarly, the ECU that controls the window stores data containing the initial information including a fully-opened and fully-closed position of the window, and the like in a storage unit including a non-volatile storage medium such as the EEPROM, and stores the data indicating the state of the window (position in up and down direction (vertical direction) of the window, and the like) at the time of the engine startup in the temporary storage unit including a volatile storage medium such as the RAM.
When the passenger performs the operation of fully opening or fully closing the window, the ECU moves the window to the fully-opened or fully-closed position based on the data stored in the storage unit and the data stored in the temporary storage unit.
As described above, the data containing the initial information, the setting information and the like of each unit of the vehicle are held in a non-volatile storage unit that normally does not require power to hold the data in terms of the importance of the data. The data indicating the state of each unit of the vehicle at the time of the engine startup is held in the volatile storage unit that requires power at all times to hold the data in terms of a capacity of the data, a cost, and the like.
The engine normally includes a startup motor for engine startup, and a crankshaft for converting the power (e.g., power generated by reciprocating motion of piston) generated after startup to a rotation force, where the startup motor starts up at the time of the engine startup so that the crankshaft starts to rotate. The operation at the time of the engine startup is hereinafter referred to as “cranking”.
However, since a supply voltage from a power supply device (battery) to the startup motor rises by the cranking at the time of the engine startup, the supply voltage from the power supply device to the ECU for controlling the seat, the window, and the like sometimes temporarily (time in unit of 1/1000 second) lowers to a voltage value lower than a minimum voltage required for the operation of the ECU. Thus, the ECU supplied with power from the power supply device becomes inoperable due to the lowering in voltage, whereby the power supply from the ECU to the temporary storage unit stops and the temporary storage unit cannot hold the stored data. That is, the data stored in the temporary storage unit disappears.
Therefore, if the data indicating the state of each unit of the vehicle at the time of the engine startup is not normally obtained (disappeared), the ECU cannot control each unit of the vehicle based on the data stored in the non-volatile storage unit and the data stored in the volatile storage unit. Thus, the seat cannot be accurately moved to a predetermined position (position set in advance by passenger and the like), and that the window cannot be stopped accurately at the fully-opened or fully-closed position when the operation of fully opening or fully closing the window is performed.
Therefore, in order to prevent disappearing of data indicating the state of each unit of the vehicle at the time of the engine startup in such a control system, in Japanese Unexamined Patent Publication No. 11-219238, if the power supply voltage of the integrated circuit is greater than or equal to a storage holding voltage of the volatile storage unit, this is detected and an instructing voltage accumulated in an accumulator is held at a predetermined first state, whereas if the power supply voltage of the integrated circuit becomes lower than the storage holding voltage of the volatile storage unit by the cranking at the time of the engine startup, this is detected and the instructing voltage accumulated in the accumulator is discharged to a predetermined second state to hold the data stored in the volatile storage unit.
In Japanese Unexamined Patent Publication No. 2001-158310, in a power management system in which a main limiting output voltage is generated according to a main input voltage and the power is supplied to a main processor board by a main voltage regulator, and a secondary limiting output voltage is generated according to a secondary input voltage and the power is supplied to the volatile RAM at least during the startup of the engine by a secondary voltage regulator, the main voltage regulator supplies the main limiting output voltage when the main input voltage is within a main voltage range and the secondary voltage regulator supplies the secondary limiting output voltage when the secondary input voltage is within a secondary voltage range including a voltage value lower than the main voltage width, and when the main processor board detects the signal related to cranking at the time of the engine startup, a predetermined device controlled by the main processor board is shut down, and the most recent state of the predetermined device is stored in the volatile RAM.